Did Swift measure gamma-ray burst prompt emission radii?

被引：59

作者：

Lyutikov, M.

机构：

[1] Univ British Columbia, Vancouver, BC V6T 1Z1, Canada

[2] Univ Rochester, Dept Phys & Astron, Rochester, NY 14627 USA

来源：

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | 2006年 / 369卷 / 01期

关键词：

gamma-rays; bursts;

D O I：

10.1111/j.1745-3933.2006.00161.x

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

The Swift X-Ray Telescope often observes a rapidly decaying X-ray emission stretching to as long as t similar to 10(3) s after a conventional prompt phase. This component is most likely due to a prompt emission viewed at large observer angles theta > 1/Gamma, where theta similar to 0.1 is a typical viewing angle of the jet and Gamma >= 100 is the Lorentz factor of the flow during the prompt phase. This can be used to estimate the prompt emission radii, r(em) >= 2tc/theta(2) similar to 6 x 10(15) cm. These radii are much larger than is assumed within the framework of a fireball model. Such large emission radii can be reconciled with a fast variability, on time-scales as short as milliseconds, if the emission is beamed in the bulk outflow frame, e.g. because of a random relativistic motion of 'fundamental emitters'. This may also offer a possible explanation for X-ray flares observed during early afterglows.

引用

页码：L5 / L8

页数：4

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